1. Field of the Invention
The present invention relates to a high-sensitivity MEMS-type z-axis vibration sensor and a method of fabricating the same, and more particularly, to a MEMS-type z-axis vibration sensor that is capable of sensing low vibration in a low frequency band by minimizing an error made by center mass by adding a part of an upper silicon layer of an SOI substrate to the center mass of a center ground electrode, and a method of fabricating the same.
2. Discussion of Related Art
Micro-electromechanical systems (MEMS) refer to the integration of mechanical elements, sensors, actuators, and electronics on a silicon substrate through microfabrication technology.
The MEMS technology is applied to various fields. Since MEMS-type vibration sensors (acceleration sensors) have been applied to gaming and mobile phones, they are closely affecting everyday life in recent times.
However, the MEMS-type vibration sensors which have been developed so far are mostly comb-drive type x- or y-axis vibration sensors sensing lateral vibration. There has been little research on z-axis vibration sensors sensing vertical vibration.
Particularly, MEMS-type z-axis vibration sensors which have been developed so far are well suited to constantly vibrating environments such as an automobile, but are not suited to an environment having very low vibration in a low frequency band and a low vibration speed like seismic waves. This is because the development of the MEMS technology has made it possible to scale down devices, but as a sensor becomes smaller, a sensitivity characteristic to a low frequency wave becomes worse.
Therefore, there is a need of a MEMS-type z-axis vibration sensor which is capable of sensibly responding to low vibration in a low frequency band.